Hole formers and placement ring assemblies are well known in the manhole casting field and are typically respectively utilized to accurately define an opening within a manhole base or the like and further to accurately position a manhole pipe connector gasket or hole former having a portion thereof to be embedded within the cast material.
Placement ring assemblies are conventionally formed of a metallic material and comprise first and second placement rings. A pipe connector gasket is positioned between cooperating circumferential portions of the rings and is maintained firmly clamped between the cooperating placement rings by a suitable locking member such as a wedge-shaped member inserted into an elongated slot provided in one of the placement rings which extends through a slot on a member provided in the cooperating placement ring. The placement rings can also be held together by a nut and bolt assembly. This arrangement necessitates an operation in which the wedge-shaped member must be inserted and hammered into position to assure firm engagement of the pipe connector gasket between the placement rings and subsequently to be removed by hammering. In addition, cast material as well as any other contaminants make it difficult to disassemble the placement rings after the cast member has been set.
Hole formers are used to make an opening for pipes to be mortared into place and packed in gaskets.